Auto Entrepreneur and Invoicing a Family SARL

I am an Auto entrepreneur, but there is one thing I am confused about. I am the minor shareholder in my husband's SARL. Am I allowed to invoice his company for my admin. services under my auto entrepreneur status providing I have other customers as well?

I've done it once without any problems, but now 2 years later our accountant is telling me that I can't do that, but he never picked up on it the first time round.